Nutmeg (Myristica fragrans) seeds contain myristic acid, trymiristin, fatty acid glycerides and an essential oil, thought to be responsible for nutmeg intoxication, containing myristicin, elemicin, eugenol, safrole. Mace is a similar spice made from the dried covering of the nutmeg seed. Nutmeg has no specific lactation-related uses. No data exist on the excretion of any components of nutmeg into breastmilk or on the safety and efficacy of nutmeg in nursing mothers or infants. Nutmeg, mace and their oils are "generally recognized as safe" (GRAS) as food ingredients by the U.S. Food and Drug Administration. High doses (e.g., a spoonful) of nutmeg can cause intoxication that includes anticholinergic symptoms. Anticholinergics may reduce lactation.[1,2] In vitro studies found that nutmeg may have antiprogesterone activity,[3] which also theoretically could affect lactation. Nutmeg and mace in amounts higher than those found in foods as a flavoring should be avoided during breastfeeding.
Dietary supplements do not require extensive pre-marketing approval from the U.S. Food and Drug Administration. Manufacturers are responsible to ensure the safety, but do not need to prove the safety and effectiveness of dietary supplements before they are marketed. Dietary supplements may contain multiple ingredients, and differences are often found between labeled and actual ingredients or their amounts. A manufacturer may contract with an independent organization to verify the quality of a product or its ingredients, but that does not certify the safety or effectiveness of a product. Because of the above issues, clinical testing results on one product may not be applicable to other products. More detailed information about dietary supplements is available elsewhere on the LactMed Web site.